JPH08208995A - Semiconductive silicone elastomer composition and production thereof - Google Patents

Abstract

PURPOSE: To obtain a semiconductive silicone elastomer composition giving a semiconductive silicone elastomer in which a conductive substance has been well homogeneously dispersed and which has a reduced unevenness of volume resistivity. CONSTITUTION: This composition comprises an organopolysiloxane having two or more Si-bonded aliphatic unsaturated hydrocarbon groups per molecule, an organohydrogenpolysiloxane having two or more Si-bonded hydrogen atoms per molecule, and a conductive substance comprising 1-10wt.% conductive carbon and 90-99wt.% conductive filler which is not carbon and has a volume resistivity of 10<1> -100<8> Ω.cm, the amount of the conductive substance being 20-60wt.% based on the whole composition. This composition gives a semiconductive silicone elastomer having a volume resistivity distribution of 1-10 in the range of 10<5> -10<10> Ω.cm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-curable semiconductive silicone elastomer composition which is cured by a hydrosilylation reaction and a method for producing the same, and more specifically, it has a volume resistivity in the range of 10 ⁵ to 10 ¹⁰ Ω · cm. The present invention relates to a semiconductive silicone elastomer composition which provides a semiconductive silicone elastomer having stable semiconductivity and less variation in volume resistivity, and a method for producing the same.

[0002]

2. Description of the Related Art Silicone rubber is used in many fields as an electrically insulating rubber because it is excellent in heat resistance, cold resistance, weather resistance and electric insulation. When imparting conductivity to the silicone rubber, as the conductivity-imparting agent, a π electron transfer type conductive substance such as carbon black, graphite powder, carbon fiber, silver, nickel, copper, zinc, iron, gold, silicon, etc. A free electron transfer type conductive substance such as metal powder or metal flakes, a compound typified by an oxide of the above metal or the like can be used, and a silicone elastomer composition to which these are added is widely used as a conductive silicone elastomer composition. Used in the field.

However, a semiconductive silicone elastomer having a volume resistivity of 10 ⁵ to 10 ¹⁰ Ωcm, which is a semiconductive region, and a variation in this value is small has not been obtained so far. The semiconductive silicone elastomer having the above volume resistivity can be obtained, for example, by adjusting the addition amount of conductive carbon black, but the volume resistivity varies depending on the lot,
There is a problem that the volume resistivity fluctuates when molding the silicone elastomer composition.

Further, Japanese Patent Application Laid-Open No. 63-156858 proposes a method of blending a crosslinked silicone rubber crushed product containing carbon black with a silicone rubber composition. The diameter is 0.
Since it is as large as 3 mm, dispersibility is poor when it is added to a liquid silicone elastomer composition, and thus it is difficult to obtain a silicone elastomer having a small variation in volume resistivity.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a semiconductive silicone elastomer composition which provides a semiconductive silicone elastomer in which a conductive substance is well and uniformly dispersed in a silicone elastomer and has a small variation in volume resistivity, and a method for producing the same.

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, have two aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule. Organopolysiloxane containing one or more and 1
In the case of producing a semiconductive silicone elastomer composition containing an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms in the molecule and a conductive substance, the conductive carbon 1 is used as the conductive substance. ~
90% to 99% by weight of conductive filler other than conductive carbon having a volume resistivity of 10 ¹ to 10 ⁸ Ω · cm and 10% by weight
And the content of the conductive filler is 20 to 60% by weight of the total composition, and when the composition further contains a non-conductive inorganic filler, It was found that it is effective to set the amount to 50 to 80% by weight of the total amount of the conductive substance and the inorganic filler, and in particular, as a method for producing the same, a fat bonded to a silicon atom in one molecule. A part or all of the organopolysiloxane containing two or more group unsaturated hydrocarbon groups and the conductive carbon are kneaded under heating at 100 to 200 ° C., then cooled to room temperature, and then 10 ¹ ~ 10 ⁸ Ω
A volume resistivity distribution in the range of 10 ⁵ to 10 ¹⁰ Ω · cm by adopting a method of adding a conductive filler other than conductive carbon having a volume specific resistance value of 10 cm and remixing at 0 to 60 ° C. The present invention was found to provide a semiconductive silicone elastomer having a volume resistivity distribution of 1 to 10 (the ratio between the maximum value and the minimum value of the volume resistivity of the semiconductive silicone elastomer). It was the eggplant.

Accordingly, the present invention provides an organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule and two hydrogen atoms bonded to a silicon atom in one molecule. In the semiconductive silicone elastomer composition containing the above-mentioned organohydrogenpolysiloxane and a conductive substance, the conductive substance is
Conductive carbon 1 to 10% by weight and volume resistivity value 10
^1-10 together consist ⁸ Omega · cm-conductive filler 90 to 99% by weight of non-carbon and the constituted by the conductive material is blended 20-60% by weight of the total composition, 10 ⁵
A semiconductive silicone elastomer composition characterized by providing a semiconductive silicone elastomer having a volume resistivity distribution of 1 to 10 in the range of 10 to 10 ¹⁰ Ω · cm, and bonding with a silicon atom in one molecule. After kneading a part or all of the organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups and conductive carbon under heating at 100 to 200 ° C, room temperature (for example, 0 to 40 ° C) Semi-conductive, characterized in that the conductive filler other than the conductive carbon having a volume resistivity value of 10 ¹ to 10 ⁸ Ω · cm is added thereto and remixed at 0 to 60 ° C. A method for producing a silicone elastomer composition is provided.

The present invention will be described in more detail below. The semiconductive silicone elastomer composition of the present invention comprises (A)
Organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, (B) 1
Organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms in the molecule, (C) conductive carbon, (D) conductive filler other than conductive carbon, 10 ¹ to 10 ⁸ Ω · cm It has a volume resistivity of.

The organopolysiloxane having two or more aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in the molecule of component (A) is the main component of the silicone elastomer composition of the present invention. Is. As this organopolysiloxane, ^one having an average composition formula represented by R ¹ _a SiO _{(4-a) / 2} is used. In this formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and at least two of R ¹ are aliphatic unsaturated hydrocarbon groups. In this case, examples of the unsaturated hydrocarbon group include alkenyl groups such as vinyl group, allyl group and isopropenyl group. Further, as the organic group R ¹ other than the unsaturated hydrocarbon group, an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an aryl group such as a phenyl group and a tolyl group, or a hydrogen atom of these organic groups Examples thereof include a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group in which a part or all of is substituted with a halogen atom or a cyano group. In addition, a is 1 to 3, preferably 1.9.
Is a positive number of ˜2.1.

The above-mentioned organopolysiloxane preferably has a linear structure, but may partially have a branched or cyclic skeleton. The viscosity of this organopolysiloxane at 25 ° C. is preferably 200,000 to 200,000 centistokes (cs), and particularly preferably 100 to 100,000 cs.

On the other hand, the organohydrogenpolysiloxane having two or more hydrogen atoms (that is, SiH groups) bonded to silicon atoms in the molecule of the component (B) is used as a crosslinking agent for the organopolysiloxane of the component (A). It is a component. Examples of the organic group bonded to a silicon atom other than a hydrogen atom include those similar to the organic group R ^{1 in the} component (A), preferably those having no aliphatic unsaturated bond, and known organo groups include Hydrogen polysiloxane can be used.

The structure of the organohydrogenpolysiloxane as the component (B) is generally linear, but may have a branched, cyclic or three-dimensional network skeleton. The degree of polymerization (the number of silicon atoms in the molecule) is preferably 3 to 300.

The blending amount of the component (B) is such that the molar ratio of the hydrogen atom bonded to the silicon atom in the component (B) and the aliphatic unsaturated hydrocarbon group bonded to the silicon atom in the component (A) is 10: 1. ~
The amount is preferably in the range of 1:10, preferably 3: 1 to 1: 3.

Further, a catalytic amount of a hydrosilylation reaction catalyst such as a platinum compound, a rhodium compound or a palladium compound is usually added to the composition of the present invention.

As platinum or a platinum-based compound, known compounds can be used. Specifically, platinum black, chloroplatinic acid,
Examples thereof include alcohol modified products of chloroplatinic acid and complexes of chloroplatinic acid with olefins, aldehydes, vinyl siloxanes, acetylene alcohols and the like.

The amount of platinum or a platinum-based compound, rhodium compound, or palladium compound added is a catalytic amount and can be appropriately increased or decreased according to the desired curing rate. Usually, platinum is added to the component (A). Amount, rhodium amount or palladium amount, 0.1 to 1000 ppm, especially 1 to 50 ppm
It is preferable to set the range to 0 ppm.

Thus, the semiconductive silicone elastomer composition of the present invention is mixed with a conductive substance. In the present invention, the conductive substance (C) has a volume resistivity of 10 ¹ Ω. A combination of conductive carbon having a size of less than cm and (D) a conductive filler other than the conductive carbon is used.

In this case, the conductive carbon as the component (C) is not particularly limited, and any of commonly used graphites, carbon blacks such as acetylene black, oil furnace black and anthracene black may be used. One of these may be used alone or in combination of two or more, and acetylene black and oil furnace black are particularly preferably used.

On the other hand, as the conductive filler other than the conductive carbon as the component (D), the volume resistivity value is 10 ¹ to ¹ 1.
To use one of the 0 ⁸ Ω · cm. Specific examples of such conductive filler include conductive zinc white, titanium black, black iron oxide, tin oxide, metal oxides such as antimony oxide, germanium, and other metal oxides such as magnetite powder. Of these, metal oxides are particularly preferably used. These conductive fillers can be blended alone or in combination of two or more.

Here, the compounding amount of the above-mentioned conductive substance (conductive carbon and conductive filler) is 20 to 20% of the whole composition.
60% (% by weight, the same applies hereinafter). If less than 20%, the resulting silicone elastomer is an insulating elastomer (that is, one having a volume resistivity of more than 10 ¹⁰ Ω · cm).
And when it is more than 60%, the conductive elastomer (ie,
It has a disadvantage that the volume resistivity becomes less than 10 ⁵ Ω · cm).

The ratio of the component (C) to the component (D) is 1-10% of the former, preferably 2-7%, and 90 of the latter.
˜99%, more preferably 93 to 98%. (D)
If the ratio of the components is less than 90%, the silicone elastomer becomes conductive, and if it exceeds 99%, it becomes insulating.
Since it is difficult to obtain a semiconductivity of 0 ⁵ to 10 ¹⁰ Ω · cm, the object of the present invention cannot be achieved.

When a non-conductive inorganic filler having a volume resistivity of more than 10 ⁸ Ω · cm, such as silica fine powder described later, is added to the composition of the present invention, the compounding amount of the component (D) is the above-mentioned conductive amount. 50-80 of the total amount of the organic substance and the inorganic filler
It is preferable to set the weight%. The blending amount of component (D) is 5
If it is less than 0% by weight, it may be difficult to sufficiently exhibit semiconductivity, and if it exceeds 80% by weight, the reinforcing property of the silicone elastomer may be deteriorated and the strength itself may be deteriorated.

In the silicone elastomer composition of the present invention, if necessary, a fine silica powder, a non-conductive inorganic filler such as calcium carbonate, etc., as described above, is added to 100 parts (parts by weight of the organopolysiloxane of component (A) above). The same applies hereinafter), 0 to 200 parts, more preferably 5 to 100 parts, still more preferably 10 to 80 parts.

Further, nitrogen-containing compounds, acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates,
It is optional to add a hydrosilylation reaction control agent such as a tin compound, a mercury compound or a sulfur compound, a heat-resistant agent such as iron oxide or cerium oxide, an adhesiveness-imparting agent, a thixotropy-imparting agent or the like.

In order to produce the semiconductive silicone elastomer composition of the present invention, first, a part or all of the organopolysiloxane of the component (A) and the conductive carbon of the component (C) are mixed to obtain 100 to 100 parts by weight. Knead by heating to 200 ° C. In this case, the kneading time can be 1 to 5 hours. After kneading, room temperature (usually 0 to 40 ° C., especially 5 to 5 ° C.)
The base compound can be obtained by cooling to (30 ° C.), then adding the component (D), and further kneading at 0 to 50 ° C. for 1 to 5 hours. A semiconductive silicone elastomer composition can be obtained by adding the rest of the component (A), the organohydrogensiloxane of the component (B), and a hydrosilylation reaction catalyst to the base compound thus obtained.

That is, in the compounding amounts of the above components (C) and (D), the conductive carbon as the component (C) and the conductive filler as the component (D) are simultaneously added to a part or all of the component (A). When added and subjected to heat treatment at 100 to 200 ° C., the obtained silicone elastomer becomes a material having a volume resistivity in the insulating region, that is, a volume resistivity exceeding 10 ¹⁰ Ω · cm, while no heat treatment is required. , The obtained silicone elastomer has a volume resistivity in the conductive region, that is, 10 ⁵ Ω
-The material has a volume resistivity smaller than cm. Further, it is difficult for these methods to widely stabilize the volume resistivity distribution. On the other hand, by kneading either one of the above-mentioned components (C) and (D) with a part or all of the component (A) and heat-treating, 10 ⁵ to 1
A silicone elastomer having a semiconductivity of 0 ¹⁰ Ω · cm is obtained. In this case, the conductive carbon of the component (C) is heat-treated with a part or all of the component (A),
It is recommended to employ the above-mentioned method, because the volume resistivity can be less varied and can be stabilized, and the volume resistivity distribution can be in the range of 1 to 10, particularly 2 to 5.

Here, in the present invention, the volume resistivity distribution means a ratio of the maximum value to the minimum value of the measured volume resistivity of the cured product of the silicone elastomer, and this measured value has the same curing value. It is desirable to measure at least 10 or more locations at different locations, or at least 10 or more cured products cured under the same composition and curing conditions.

When a part of the component (A) is kneaded with the component (C), it is preferable to use 10 to 90% of the component (A). When the non-conductive inorganic filler is blended, it may be blended with the component (C) or the component (D).

When the semiconductive silicone elastomer composition is to be cured, it is heated at 60 to 200 ° C. for 1 to 20 minutes and subjected to primary vulcanization such as press molding, and then 150 if necessary.
A method of secondary vulcanization at ˜250 ° C. for 2 to 7 hours can be adopted.

The obtained silicone elastomer has 10
^It has a semi-conductivity of ⁵ to 10 ¹⁰ Ω · cm, and has a very small volume resistivity distribution in this range and is stable at 1 to 10. Therefore, the semiconductive silicone elastomer composition of the present invention is suitably used for applications such as paper feed rollers, transfer rollers, developing rollers and fixing rollers for preventing paper wrapping in PPC, printers, facsimiles and the like.

[0031]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

In the following example, the volume resistivity is
It was measured by the following method in accordance with the Japan Rubber Association standard SRIS 2301-1969. Also, rubber hardness (JIS
A hardness meter is used), tensile strength, elongation, compression set is JI
It carried out according to the method described in SK-6301. Method for Measuring Volume Resistivity As shown in FIG. 1, a test piece 1 having a length of 150 mm, a width of 20 mm, and a thickness of 0.5 to 1.0 mm is sandwiched between an upper electrode 2 and a lower electrode 3. The upper electrode 2 has a length of 30 mm and a width of 15 m
A pair of current terminals 2a, 2a having a thickness of 5 mm and a thickness of 5 mm are attached to an insulator 4 such as polyethylene, and a weight 5 is placed on the insulator 4 so that a weight of 5 kg is applied to the current terminals 2a, 2a. On the other hand, the lower electrode 3 has a length of 30 mm and a width of 15 m.
m, a pair of current terminals 3a, 3a having a thickness of 5 mm and a length of 30
mm, width 5 mm, a pair of knife-shaped voltage terminals 3b, 3b
And the current terminals 3a, 3a are arranged so as to face the current terminals 2a, 2a of the upper electrode 2, respectively. In addition, on the test piece 1 with an insulating plate 6 interposed, 0.5
A weight 7 of kg is placed, and the lower electrode 3 is set on the insulating plate 8. In this state, the upper electrode 2 and the lower electrode 3 are connected and the volume resistivity is measured.

[Example 1] Carbon black (Ketjenblack EC-600JD, Lion Akzo Co., Ltd.)
1.2 g, a linear dimethylpolysiloxane containing (CH ₂ ═CH) (CH ₃ ) SiO _2/2 units and blocked at both ends with trimethylsilyl groups (viscosity 10,000 cs, vinyl group equivalent 0.0094 mol / 60 g of 100 g) and 30 g of crystalline silica were kneaded at 150 ° C. for 2 hours. Then 2
Cooled to 5 ℃, conductive zinc white (volume resistivity 60Ω
Cm (under a pressure of 570 kg / cm ² )) was added and mixed, and then uniformly dispersed with a triple roll at 25 ° C. to obtain a base compound A.

The products shown in Table 1 in this base compound A
The quality was blended in the amounts shown in Table 1, 120 ° C, 100 kg / c
m² After press vulcanizing for 10 minutes at 200 ° C for 4 hours 2
Next vulcanization, total of 10 silicone elastomer sheets
The sheet was manufactured and the volume resistivity of these sheets was measured. The result
It is also shown in Table 1.

Example 2 In Example 1, titanium black (volume specific resistance of 90Ω.
cm (under a pressure of 570 kg / cm ² )) was used, and 10 base compounds B and silicone elastomer sheets were manufactured in the same manner as in Example 1 and the volume resistivity was measured. The results are also shown in Table 1.

Comparative Example 1 2.5 g of carbon black,
The same vinyl group-containing dimethylpolysiloxane as used in Example 1 (60 g) and crystalline silica (90 g) were kneaded at 150 ° C. for 2 hours, and then uniformly dispersed at 25 ° C. with a three-roll mill to prepare a base compound C. .

The base compound C was mixed with the substances shown in Table 1 and vulcanized under the same conditions as in Example 1 to produce 10 silicone elastomer sheets, and the volume resistivity was measured in the same manner as in Example 1. did. The results are also shown in Table 1.

[Comparative Example 2] All the raw materials of the base compound A in Example 1 were mixed and the same procedure as in Example 1 was repeated.
The base compound D was manufactured by kneading for 2 hours under heating at 50 ° C., 10 sheets were manufactured in the same manner as in Example 1, and the volume resistivity was measured. The results are also shown in Table 1.

[Comparative Example 3] All the raw materials of the base compound A in Example 1 were kneaded at 25 ° C without heating,
The base compound E was manufactured, 10 sheets were manufactured in the same manner as in Example 1, and the volume resistivity was measured. The results are also shown in Table 1.

[0040]

[Table 1]

[0041]

According to the present invention, a semiconductive silicone elastomer composition is obtained in which a conductive substance is well and uniformly dispersed in a silicone elastomer to give a semiconductive silicone elastomer having a small variation in volume resistivity. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a method for measuring volume resistivity.

[Explanation of symbols]

 1 Test piece 2 Upper electrode 3 Lower electrode

Front page continuation (72) Inventor Hajime Saito 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (4)

[Claims] 1. An organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and an organopolysiloxane containing two or more hydrogen atoms bonded to a silicon atom in one molecule. In a semiconductive silicone elastomer composition containing hydrogen polysiloxane and a conductive substance, the conductive substance has a conductive carbon content of 1 to 10% by weight and a volume resistivity value of 10 ¹ to 10 ⁸ Ω · c.
m of the conductive filler other than the conductive carbon of 90 to 99% by weight, and the conductive substance of 20 to 60% by weight based on the total weight of the composition. 10 ⁵ to 10 ¹⁰ Ω · c
A semiconductive silicone elastomer composition, which provides a semiconductive silicone elastomer having a volume resistivity distribution of 1 to 10 in the range of m. 2. The composition further comprises a non-conductive inorganic filler, and the content of the conductive filler is 50 to 80% by weight of the total amount of the conductive substance and the inorganic filler. The semiconductive silicone elastomer composition according to 1. 3. The conductive filler other than conductive carbon is one or more selected from conductive zinc white, titanium black, black iron oxide, tin oxide, antimony oxide, germanium, and magnetite. Or the semiconductive silicone elastomer composition described in 2. 4. A part or all of an organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule and 100 to 2 of conductive carbon.
After kneading under heating at 00 ° C., cooling to room temperature, and then adding conductive filler other than conductive carbon having a volume resistivity value of 10 ¹ to 10 ⁸ Ω · cm to 0 to
A method for producing a semiconductive silicone elastomer composition, which comprises remixing at 60 ° C.